| Message ID | 20200904133052.20299-1-snu@amazon.com |
|---|---|
| State | Not Applicable |
| Delegated to: | David Miller |
| Headers | show |
| Series | net/packet: fix overflow in tpacket_rcv | expand |
On Fri, Sep 04, 2020 at 03:30:52PM +0200, Stefan Nuernberger wrote: > From: Or Cohen <orcohen@paloaltonetworks.com> > > Using tp_reserve to calculate netoff can overflow as > tp_reserve is unsigned int and netoff is unsigned short. > > This may lead to macoff receving a smaller value then > sizeof(struct virtio_net_hdr), and if po->has_vnet_hdr > is set, an out-of-bounds write will occur when > calling virtio_net_hdr_from_skb. > > The bug is fixed by converting netoff to unsigned int > and checking if it exceeds USHRT_MAX. > > This addresses CVE-2020-14386 > > Fixes: 8913336a7e8d ("packet: add PACKET_RESERVE sockopt") > Signed-off-by: Or Cohen <orcohen@paloaltonetworks.com> > Signed-off-by: Eric Dumazet <edumazet@google.com> > > [ snu: backported to 4.9, changed tp_drops counting/locking ] > > Signed-off-by: Stefan Nuernberger <snu@amazon.com> > CC: David Woodhouse <dwmw@amazon.co.uk> > CC: Amit Shah <aams@amazon.com> > CC: stable@vger.kernel.org > --- > net/packet/af_packet.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) What is the git commit id of this patch in Linus's tree? thanks, greg k-h
On Fri, 2020-09-04 at 16:16 +0200, Greg Kroah-Hartman wrote: > On Fri, Sep 04, 2020 at 03:30:52PM +0200, Stefan Nuernberger wrote: > > > > From: Or Cohen <orcohen@paloaltonetworks.com> > > > > Using tp_reserve to calculate netoff can overflow as > > tp_reserve is unsigned int and netoff is unsigned short. > > > > This may lead to macoff receving a smaller value then > > sizeof(struct virtio_net_hdr), and if po->has_vnet_hdr > > is set, an out-of-bounds write will occur when > > calling virtio_net_hdr_from_skb. > > > > The bug is fixed by converting netoff to unsigned int > > and checking if it exceeds USHRT_MAX. > > > > This addresses CVE-2020-14386 > > > > Fixes: 8913336a7e8d ("packet: add PACKET_RESERVE sockopt") > > Signed-off-by: Or Cohen <orcohen@paloaltonetworks.com> > > Signed-off-by: Eric Dumazet <edumazet@google.com> > > > > [ snu: backported to 4.9, changed tp_drops counting/locking ] > > > > Signed-off-by: Stefan Nuernberger <snu@amazon.com> > > CC: David Woodhouse <dwmw@amazon.co.uk> > > CC: Amit Shah <aams@amazon.com> > > CC: stable@vger.kernel.org > > --- > > net/packet/af_packet.c | 9 ++++++++- > > 1 file changed, 8 insertions(+), 1 deletion(-) > What is the git commit id of this patch in Linus's tree? > Sorry, this isn't merged on Linus' tree yet. It's a heads up that the backport isn't straightforward. Best, Stefan > thanks, > > greg k-h Amazon Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B Sitz: Berlin Ust-ID: DE 289 237 879
On Fri, Sep 04, 2020 at 02:22:46PM +0000, Nuernberger, Stefan wrote: > On Fri, 2020-09-04 at 16:16 +0200, Greg Kroah-Hartman wrote: > > On Fri, Sep 04, 2020 at 03:30:52PM +0200, Stefan Nuernberger wrote: > > > > > > From: Or Cohen <orcohen@paloaltonetworks.com> > > > > > > Using tp_reserve to calculate netoff can overflow as > > > tp_reserve is unsigned int and netoff is unsigned short. > > > > > > This may lead to macoff receving a smaller value then > > > sizeof(struct virtio_net_hdr), and if po->has_vnet_hdr > > > is set, an out-of-bounds write will occur when > > > calling virtio_net_hdr_from_skb. > > > > > > The bug is fixed by converting netoff to unsigned int > > > and checking if it exceeds USHRT_MAX. > > > > > > This addresses CVE-2020-14386 > > > > > > Fixes: 8913336a7e8d ("packet: add PACKET_RESERVE sockopt") > > > Signed-off-by: Or Cohen <orcohen@paloaltonetworks.com> > > > Signed-off-by: Eric Dumazet <edumazet@google.com> > > > > > > [ snu: backported to 4.9, changed tp_drops counting/locking ] > > > > > > Signed-off-by: Stefan Nuernberger <snu@amazon.com> > > > CC: David Woodhouse <dwmw@amazon.co.uk> > > > CC: Amit Shah <aams@amazon.com> > > > CC: stable@vger.kernel.org > > > --- > > > net/packet/af_packet.c | 9 ++++++++- > > > 1 file changed, 8 insertions(+), 1 deletion(-) > > What is the git commit id of this patch in Linus's tree? > > > > Sorry, this isn't merged on Linus' tree yet. It's a heads up that the > backport isn't straightforward. Ok, please be more specific about this when sending patches out... greg k-h
Hi, On Fri, Sep 04, 2020 at 04:36:48PM +0200, gregkh@linuxfoundation.org wrote: > On Fri, Sep 04, 2020 at 02:22:46PM +0000, Nuernberger, Stefan wrote: > > On Fri, 2020-09-04 at 16:16 +0200, Greg Kroah-Hartman wrote: > > > On Fri, Sep 04, 2020 at 03:30:52PM +0200, Stefan Nuernberger wrote: > > > > > > > > From: Or Cohen <orcohen@paloaltonetworks.com> > > > > > > > > Using tp_reserve to calculate netoff can overflow as > > > > tp_reserve is unsigned int and netoff is unsigned short. > > > > > > > > This may lead to macoff receving a smaller value then > > > > sizeof(struct virtio_net_hdr), and if po->has_vnet_hdr > > > > is set, an out-of-bounds write will occur when > > > > calling virtio_net_hdr_from_skb. > > > > > > > > The bug is fixed by converting netoff to unsigned int > > > > and checking if it exceeds USHRT_MAX. > > > > > > > > This addresses CVE-2020-14386 > > > > > > > > Fixes: 8913336a7e8d ("packet: add PACKET_RESERVE sockopt") > > > > Signed-off-by: Or Cohen <orcohen@paloaltonetworks.com> > > > > Signed-off-by: Eric Dumazet <edumazet@google.com> > > > > > > > > [ snu: backported to 4.9, changed tp_drops counting/locking ] > > > > > > > > Signed-off-by: Stefan Nuernberger <snu@amazon.com> > > > > CC: David Woodhouse <dwmw@amazon.co.uk> > > > > CC: Amit Shah <aams@amazon.com> > > > > CC: stable@vger.kernel.org > > > > --- > > > > net/packet/af_packet.c | 9 ++++++++- > > > > 1 file changed, 8 insertions(+), 1 deletion(-) > > > What is the git commit id of this patch in Linus's tree? > > > > > > > Sorry, this isn't merged on Linus' tree yet. It's a heads up that the > > backport isn't straightforward. > > Ok, please be more specific about this when sending patches out... The commit is in Linux' tree now as acf69c946233259ab4d64f8869d4037a198c7f06 . Older stable series, which do not have 8e8e2951e309 ("net/packet: make tp_drops atomic") will though need a backport as per above AFICS. Regards, Salvatore
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index fb643945e424..b5b79f501541 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2161,7 +2161,8 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, int skb_len = skb->len; unsigned int snaplen, res; unsigned long status = TP_STATUS_USER; - unsigned short macoff, netoff, hdrlen; + unsigned short macoff, hdrlen; + unsigned int netoff; struct sk_buff *copy_skb = NULL; struct timespec ts; __u32 ts_status; @@ -2223,6 +2224,12 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev, } macoff = netoff - maclen; } + if (netoff > USHRT_MAX) { + spin_lock(&sk->sk_receive_queue.lock); + po->stats.stats1.tp_drops++; + spin_unlock(&sk->sk_receive_queue.lock); + goto drop_n_restore; + } if (po->tp_version <= TPACKET_V2) { if (macoff + snaplen > po->rx_ring.frame_size) { if (po->copy_thresh &&